FileInfo是DirectoryInfo的子代吗

本文关键字：DirectoryInfo FileInfo | 更新日期: 2023-09-27 18:24:06

如何检查FileInfo对象是否是DirectoryInfo的后代？

public bool IsFileDescendantOfDirectory(
    FileInfo fileInfo,
    DirectoryInfo directoryInfo)
{
}

FileInfo是DirectoryInfo的子代吗

您可以浏览父目录：

public static bool IsFileDescendantOfDirectory(FileInfo fileInfo, DirectoryInfo directoryInfo)
{
    // https://connect.microsoft.com/VisualStudio/feedback/details/777308/inconsistent-behavior-of-fullname-when-provided-path-ends-with-a-backslash
    string path = directoryInfo.FullName.TrimEnd(Path.DirectorySeparatorChar);
    DirectoryInfo dir = fileInfo.Directory;
    while (dir != null)
    {
        if (dir.FullName.TrimEnd(Path.DirectorySeparatorChar).Equals(path, StringComparison.OrdinalIgnoreCase))
            return true;
        dir = dir.Parent;
    }
    return false;
}

有趣的是，您必须比较FullName，DirectoryInfo.Equals不能按预期工作，因为它使用的是仅比较引用的Object.Equals。

您可以检查文件的父级，直到它到达匹配的目录。这将比在目录中搜索文件更快：

public bool IsFileDescendantOfDirectory(DirectoryInfo directoryInfo, FileInfo fileInfo)
{
    DirectoryInfo d = fileInfo.Directory;
    do
    {
        if (d.FullName.Equals(directoryInfo.FullName, StringComparison.OrdinalIgnoreCase))
        {
            return true;
        }
        d = d.Parent;
    }
    while(d != null);
    return false;
}

经过与Tim Schmelter的反复讨论，我确信以下方法对于确定FileInfo路径是否位于DirectoryInfo路径下是有效的：

public static bool IsFileBelowDirectory(FileInfo fileInfo, DirectoryInfo directoryInfo)
{
    var separator = Path.DirectorySeparatorChar.ToString();
    var directoryPath = string.Format("{0}{1}"
    , directoryInfo.FullName
    , directoryInfo.FullName.EndsWith(separator) ? "": separator);
    return fileInfo.FullName.StartsWith(directoryPath, StringComparison.OrdinalIgnoreCase);
}

有趣的是，您不需要遍历目录来检查每个级别的质量。当您的文件显然不在目录中时，这样可以节省一些时间；例如对于目录CCD_ 6和文件CCD_。

如果你想查找名称，这将是一个简单的解决方案：

Directory
.EnumerateFiles(di.FullName, *.*, SearchOption.AllDirectories)
.Any(x => x == fileInfo.FullName);
FileInfo通过其Directory属性提供DirectoryInfo，DirectoryInfo提供Parent属性。如此公正； 
DirectoryInfo fileOwner = myFileInfo.Directory;
do
{
   if(fileOwner == mySampleDirectory) Debug.WriteLine("Yes !");
   fileOwner = fileOwner.Parent;
} 
while(fileOwner != null)

这就足够了：

    public static bool IsDirectoryParent(DirectoryInfo directoryInfo, DirectoryInfo parentInfo)
    {
        if (!directoryInfo.Name.StartsWith(parentInfo.FullName))
            return false;
        return directoryInfo.FullName == parentInfo.FullName 
            || IsDirectoryParent(directoryInfo.Parent, parentInfo);
    }
    public bool IsFileParent(FileInfo fileInfo, DirectoryInfo directoryInfo)
    {
        return IsDirectoryParent(fileInfo.Directory, directoryInfo);
    }
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